1. Field of the Invention
The present invention relates to a mobile robot and, more particularly, to an apparatus and method for calling a mobile robot.
2. Description of the Conventional Art
In general, a mobile robot is a device for automatically cleaning an area by sucking foreign substances such as dust from the floor while moving in a room (e.g., a living room) of a house by itself without user's manipulation.
In cleaning, the robot cleaner discriminates a distance from itself to an obstacle such as furniture, office supplies or a wall in a cleaning area through a distance sensor and selectively controls a motor for rotating its left wheel and a motor for rotating its right wheel according to the discriminated distance to thereby change its direction and automatically clean the cleaning area. Herein, the robot cleaner performs the cleaning operation while travelling in the cleaning area through map information stored in an internal storage unit.
For example, the robot cleaner includes a gyro sensor for sensing a direction of the robot cleaner, an encoder for determining a traveling distance by sensing the number of times of rotation of the wheel of the robot cleaner; an ultrasonic sensor for sensing a distance between the robot cleaner, a target; and an infrared ray sensor for sensing an obstacle, and other numerous sensors.
However, the conventional robot cleaner has shortcomings in that because numerous high-priced sensors are installed to perform cleaning by precisely traveling along a pre-set cleaning path, its internal structure is complicated and fabrication cost increases.
In an effort to solve such a problem, a robot cleaner has been developed to perform cleaning by traveling along an arbitrary cleaning path in a random manner.
A traveling device of the robot cleaner in accordance with a conventional art will now be described.
FIG. 1 is a block diagram showing the construction of the traveling device of a robot cleaner in accordance with a conventional art.
As shown in FIG. 1, the traveling device of a conventional robot cleaner includes: an obstacle sensing unit 1 for sensing an obstacle based on an impact amount generated when a robot cleaner going straight ahead in a specific area collides with the obstacle and generating an obstacle sense signal; a controller for stopping traveling of the robot cleaner based on the obstacle sense signal generated by the obstacle sensing unit 1, generating a random angle randomly, and generating a control signal for rotating the robot cleaner according to the random angle; a left motor driving unit 3 for rotating a left motor (ML) 5 of the robot cleaner at a certain speed according to the control signal of the controller 2; and a right motor driving unit 4 for rotating a right motor (MR) 6 of the robot cleaner at a certain speed according to the control signal of the controller 2.
FIG. 2 is a flow chart of a method for traveling a robot cleaner in accordance with the conventional art.
First, when a user inputs a cleaning command signal (step S1), the controller 2 generates a control signal to make the rotation speed of the left motor and the right motor 6 equal in order to making the robot cleaner go straight ahead, and simultaneously outputs the control signal to the left motor driving unit 3 an the right motor driving unit 4 (step S2).
The left motor driving unit 3 rotates the left motor 5 according to the control signal of the controller. At this time, the right motor driving unit 4 rotates the right motor 6 according to the control signal of the controller 2. Namely, as the left and right motors 5 and 6 are simultaneously rotated, the robot cleaner goes straight ahead.
The obstacle sensing unit senses an obstacle based on an amount of impact generated when the robot cleaner collides with the obstacle, generates an obstacle sense signal, and applies the obstacle sense signal to the controller 2 (step S3). If the obstacle sense signal is not generated, the robot cleaner continuously performs cleaning operation.
The controller 2 stops traveling of the robot cleaner according to the obstacle sense signal, generates a random angle randomly (step S4), generates a control signal for rotating the robot cleaner according to the random angle, and then outputs the generated control signal to the left and right motor driving units 3 and 4.
The left motor driving unit 3 rotates the left motor 5 according to the control signal of the controller 2, and the right motor driving unit 4 rotates the right motor 6 according to the control signal of the controller. In other words, by controlling the rotation speed of the left motor 5 and the rotation speed of the right motor 6 differently, the direction of the robot cleaner can be changed to a random angle (step S5).
Thereafter, when the robot cleaner is rotated as much as the random angle, the controller allows the robot cleaner to go straight ahead (step S6). When the cleaning operation of the robot cleaner is completed, the controller terminates the cleaning operation (step S7). If the cleaning operation of the robot cleaner is not completed, the controller allows the robot cleaner to repeatedly perform the cleaning operation.
If a user wants to move the robot cleaner to a specific place while the robot cleaner is performing the cleaning operation, the user should stop the operation of the robot cleaner and then picks up the robot cleaner personally to move it to the specific place. That is, the conventional robot cleaner has the problem that the user should personally pick up the robot cleaner and move it to a different cleaning space or a robot cleaner depository.
U.S. Pat. Nos. 5,440,216 and 5,646,494 also disclose a robot cleaner.